math
posted by Sushmitha .
What is the tip speed (ft/min) of a 21 inch long rotary lawn mower blade that is connected to the output shaft of an engine operating at 3400 rpm?
What are the steps to figure this out?

a circle of radius 21" has a circumference of 131.95" = 11 ft
so, 11ft * 3400/min = 37400 ft/min